CORESCHED(1) User Commands CORESCHED(1)

# [NAME](#NAME)

coresched - manage core scheduling cookies for tasks

# [SYNOPSIS](#SYNOPSIS)

**coresched** \[**get**] \[**-s** *pid*]

**coresched** **new** \[**-t** *type*] **-d** *pid*

**coresched** **new** \[**-t** *type*] -- *command* \[*argument*...]

**coresched** **copy** \[**-s** *pid*] \[**-t** *type*] **-d** *pid*

**coresched** **copy** \[**-s** *pid*] \[**-t** *type*] -- *command* \[*argument*...]

# [DESCRIPTION](#DESCRIPTION)

The **coresched** command is used to retrieve or modify the core scheduling cookies of a running process given its *pid*, or to spawn a new *command* with core scheduling cookies.

Core scheduling permits the definition of groups of tasks that are allowed to share a physical core. This is done by assigning a cookie to each task. Only tasks have the same cookie are allowed to be scheduled on the same physical core.

It is possible to either assign a new random cookie to a task, or copy a cookie from another task. It is not possible to choose the value of the cookie.

# [FUNCTIONS](#FUNCTIONS)

**get**

Retrieve the core scheduling cookie of the PID specified in **-s**. If **-s** is omitted, it will get the cookie of the current **coresched** process.

**new**

Assign a new cookie to an existing PID specified in **-d**, or execute *command* with a new cookie.

**copy**

Copy the cookie from an existing PID (**-s**) to another PID (**-d**), or execute *command* with that cookie. If **-s** is omitted, it will get the cookie of the current **coresched** process.

If no function is specified, it will run the **get** function.

# [OPTIONS](#OPTIONS)

**-s**, **--source** *PID*

Which *PID* to get the cookie from. If this option is omitted, it will get the cookie from the current **coresched** process.

**-d**, **--dest** *PID*

Which *PID* to modify the cookie of.

**-t**, **--dest-type** *TYPE*

The type of the PID whose cookie will be modified. This can be one of three values:

•**pid**, or process ID

•**tgid**, or thread group ID (default value)

•**pgid**, or process group ID

**-v**, **--verbose**

Show extra information when modifying cookies of tasks.

**-h**, **--help**

Display help text and exit.

**-V**, **--version**

Display version and exit.

# [EXAMPLES](#EXAMPLES)

Get the core scheduling cookie of the coresched task itself, usually inherited from its parent:

**coresched get**

Get the core scheduling cookie of a task with PID *123*:

**coresched get -s** *123*

Give a task with PID *123* a new core scheduling cookie:

**coresched new -d** *123*

Spawn a new task with a new core scheduling cookie:

**coresched new** -- *command* \[*argument*...]

Copy the cookie from the current coresched process another task with pid *456*:

**coresched copy -d** *456*

Copy the cookie from a task with pid *123* to another task with pid *456*:

**coresched copy -s** *123* **-d** *456*

Copy the cookie from a task with pid *123* to a new task *command*:

**coresched copy -s** *123* -- *command* \[*argument*...]

Copy the cookie from a task with pid *123* to the process group ID *456*:

**coresched copy -s** *123* **-t** *pgid* **-d** *456*

# [PERMISSIONS](#PERMISSIONS)

Retrieving or modifying the core scheduling cookie of a process requires **PTRACE\_MODE\_READ\_REALCREDS** ptrace access to that process. See the section "Ptrace access mode checking" in [**ptrace**(2)](/man/os/util-linux/ptrace.2) for more information.

# [EXIT STATUS](#EXIT_STATUS)

On success, **coresched** returns 0. If **coresched** fails, it will print an error and return 1.

If a *command* is being executed, the return value of **coresched** will be the return value of *command*.

# [NOTES](#NOTES)

**coresched** requires core scheduling support in the kernel. This can be enabled via the **CONFIG\_SCHED\_CORE** kernel config option.

# [AUTHORS](#AUTHORS)

*Thijs Raymakers* <thijs@raymakers.nl>, *Phil Auld* <pauld@redhat.com>

# [COPYRIGHT](#COPYRIGHT)

Copyright © 2024 Thijs Raymakers and Phil Auld. This is free software licensed under the EUPL.

# [SEE ALSO](#SEE_ALSO)

[**chrt**(1)](/man/os/util-linux/chrt.1), [**nice**(1)](/man/os/util-linux/nice.1), [**renice**(1)](/man/os/util-linux/renice.1), [**taskset**(1)](/man/os/util-linux/taskset.1), [**ptrace**(2)](/man/os/util-linux/ptrace.2), [**sched**(7)](/man/os/util-linux/sched.7)

The Linux kernel source files *Documentation/admin-guide/hw-vuln/core-scheduling.rst*

# [REPORTING BUGS](#REPORTING_BUGS)

For bug reports, use the *issue tracker* <https://github.com/util-linux/util-linux/issues>.

# [AVAILABILITY](#AVAILABILITY)

The **coresched** command is part of the util-linux package which can be downloaded from *Linux Kernel Archive* <https://www.kernel.org/pub/linux/utils/util-linux/>.

2026-10-19 util-linux 2.42.4

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Document: coresched(1) from util-linux 2.42.4-r1 (Chainguard OS)